Vehicle drive arrangement

ABSTRACT

A vehicle drive arrangement in which a drive shaft (10a) is coupled with a first hollow driven shaft (12) and a second driven shaft (11) within hollow driven shaft (12) by first (14) and second (13) coaxial clutches respectively clutch (13) which is adjacent flywheel (10) is operated by a force transmitting path in the form of pins (17) located outside both driven shafts and passing axially through the central portion (24) of clutch (14). This produces a more compact arrangement since the force transmitting path for the operation of clutch (13) does not pass around the outer periphery of clutch (14).

TECHNICAL FIELD

This invention relates to vehicle drive arrangements, hereinafterreferred to as being of the type described, in which a drive shaft isconnected with a first hollow driven shaft via a co-axial first clutchand with second driven shaft (which is rotatable within the first drivenshaft) via a co-axial second clutch.

Drive arrangements of the type described are used in, for example,agricultural or industrial tractors of the wheeled or crawler type inwhich, for example, one of the driven shaft is a gearbox input shaft andthe other driven shaft is a PTO (power take-off) shaft.

There is a requirement in such drive arrangements to operate each clutchindependently for maximum vehicle operational flexibility. Since theclutches are co-axial and normally axially adjacent each other within ahousing, access to operate one clutch is normally straightforward butthe operation of the other clutch has hitherto proved more difficult andrelatively complex and bulky arrangements have been previously proposedwhich have involved passing round the outer periphery of the one clutchto operate the other clutch.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide an improved form ofvehicle drive arrangement of the type described.

According to the present invention there is provided a vehicle drivearrangement having a drive shaft, a first hollow driven shaft, a seconddriven shaft rotatable within the first hollow driven shaft, and firstand second clutches co-axial with the driven shafts for coupling thedrive shaft with the first and second driven shafts respectively, thearrangement being characterised in that one of the clutches is operatedby a force transmitting path which is located outside both driven shaftsand which passes axially through the central portion of the otherclutch.

It will be appreciated that such an arrangement is more compact sincethe force transmitting path no longer passes around the other peripheryof the one clutch. Also, since the force transmitting path is locatedoutside both driven shafts there is no limit on the distance the twodriven shafts can be located one within the other.

In a preferred construction the first clutch is operatively connectedwith the hollow driven shaft via a central hub portion and the forcetransmitting path for the second clutch comprises operating memberswhich extend axially through the central hub portion.

The operating members may be axially displaced by an actuating componentwhich encircles the hollow driven shaft.

The actuating component may act on one end of each operating member, theother end of each operating member being operatively connected with athrust bearing for operation of the second clutch.

Each operating member may comprise a pin which is axially slidable in abore in the central hub portion.

The first clutch may be operated via a collar which encircles and slideson the actuating component.

DESCRIPTION OF THE DRAWINGS

One embodiment of the invention will now be described, by way of exampleonly, with reference to the accompanying drawing which shows a verticalsection through a dual clutch arrangement embodying the presentinvention for use in a crawler tractor.

BEST MOST OF CARRYING OUT INVENTION

Referring to the drawing a flywheel 10 is driven from an engine via adrive shaft 10a. A PTO shaft 11 passes down the centre of a hollowdriven shaft 12 which functions as a gearbox input shaft. Power istransmitted from the flywheel 10 to the PTO shaft 11, via a single platePTO friction clutch 13. The gearbox input shaft 12 is driven from theflywheel 10 via an over-centre clutch 14.

The PTO clutch 13 is disengaged by a thrust collar 15 which acts on anactuating component in the form of a sleeve 16 surrounding shaft 12. Thesleeve 16 in turn acts on a number of operating members in the form ofpins 17 which in turn are connected with a clutch release bearing 18. Torelease the PTO clutch 13, collar 15 is displaced in direction "X" usingan operating fork 19. This causes a corresponding axial displacement ofthrust bearing 18 which in turn contacts and displaces adiaphragm-spring 20 to release the pressure on clutch pressure plate 21and thus disengage the clutch 13. On return of collar 15 to the positionshown in the drawing the clutch 13 is automatically engaged bydiaphragm-spring 20.

The over-centre clutch 14 is operated by a collar 22 and an associatedfork 23. The Collar 22 surrounds sleeve 16 and is axially slidablethereon. Pressure plate 14a is integral with the central hub portion 24of clutch 14 through which pins 17 extend. The Hub portion 24 is heldaxially fixed on shaft 12 by a ring 25. Pressure plate 14b is axiallyslidable relative to hub 24 on splines 26 and is biased away by springs27 from central friction member 14c which is splined onto flywheel 10.Pressure plate 14b carries a series of circumferentially spaced arms 28which are pivotally mounted on the pressure plate 29 and are providedwith cam formations 30. Each arm 28 is connected with the collar 22 viaa tie 31 which is pivoted on the arm at 32 and on the collar at 33.

The hub 24 carries an annular abutment 34 provided with a bearingsurface 35 which is contacted by cam formations 30. When clutch 14 is inthe engaged position shown in the drawing cam formations 30 contact thebearing surface 35 and the centre of the pivot 33 is to the left of thecentre of pivot 32 as shown in the drawing.

To disengage the clutch 14 the collar 22 is moved axially in direction"Y" using the fork 23. This causes ties 31 to pivot in an anti-clockwisesense about pivot 32 as shown by arrow "S" and arms 28 to pivotclockwise about pivots 29 as shown by arrow "R". This causes the camformations 30 to disengage the bearing surface 35 thus allowing thesprings 27 to displace pressure plate 14b to the right as viewed in thedrawing thus disengaging the clutch 14.

As will be understood, when collar 22 is moved to the clutch disengagedposition pivot 33 moves over-centre to the right of pivot 32.

The present invention thus provides an improved form of vehicle drivearrangement of the type described in which the PTO clutch 13 is operatedby a force transmitting path (provided by pins 17) which passes axiallythrough the central portion of the over-centre gearbox clutch 14 thussimplifying and reducing the overall diameter of the clutch installationcompared to an arrangement in which the PTO clutch 13 is operated by alinkage which passes around the outer periphery of the clutch 14. Alsoit will be appreciated that there is no limit on the distance for whichthe driven shafts 11 and 12 can be located one within the other.

It will be understood that the roles of shafts 11 and 12 could bereversed, that is shaft 11 could be used as the gearbox input shaft andshaft 12 could be the PTO shaft. Also, the roles of clutches 13 and 14could be reversed.

What is claimed is:
 1. A vehicle drive arrangement having a drive shaft(10a), a first hollow driven shaft (12), a second driven shaft (11)rotatable within the first hollow driven shaft, first and secondclutches (13, 14) co-axial with the driven shafts for coupling the driveshaft with the first and second driven shafts respectively, one (14) ofsaid clutches being connected with its associated driven shaft via acentral hub portion (24), and the other clutch (13) being operated by aplurality of operating members (17) which passes through correspondingapertures in the central hub portion and which are located outside bothdriven shafts.
 2. An arrangement according to claim 10 characterised inthat the operating members (17) are axially displaced to operate saidother clutch (13) by an actuating component (16) which encircles thehollow driven shaft (12).
 3. An arrangement according to claim 2characterized in that the actuating component (16) acts on one end ofeach operating member (17) and the other end of each operating member isoperatively connected with a thrust bearing (18) for operation of saidother clutch (13).
 4. An arrangement according to claim 2 characterizedin that each operating member comprises a pin (17) which is axiallyslidable in a bore in the central hub portion (24).
 5. An arrangementaccording to claim 2 characterized in that said one (14) of the clutchesis operated via a collar (22) which encircles and slides on theactuating component (16).
 6. An arrangement according to claim 1characterized in that said one (14) of the clutches is operated by anover-centre linkage (28, 29, 30, 31, 32).
 7. An arrangement according toclaim 1 characterized in that the first driven shaft (12) is a vehicledrive shaft and the second driven shaft (11) is a power take-off shaft.